package cn.layfolk.nio.groupchat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;

/**
 * @Author 王津
 * @Date 2020/9/28
 * @Version 1.0
 */
public class GroupChatServer {


    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

    //构造器
    //初始化工作
    public GroupChatServer(){

        try {
            //得到选择器
            selector = Selector.open();
            //ServerSocketChannel
            listenChannel = ServerSocketChannel.open();
            //绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            //设置阻塞模式
            listenChannel.configureBlocking(false);
            //将该servcerSocketChannel注册到selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    //监听
    public void listen(){

        try {
            //循环处理
            while (true) {
                int count = selector.select();
                if (count>0){//有事件处理

                    //遍历得到selectionKey集合
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()){
                        //取出 selectionkey
                        SelectionKey key = iterator.next();

                        //监听到accept
                        if (key.isAcceptable()){
                            SocketChannel socketChannel = listenChannel.accept();
                            socketChannel.configureBlocking(false);
                            //将该channel注册到selector中
                            socketChannel.register(selector, SelectionKey.OP_READ);

                            //提示
                            System.out.println(socketChannel.getRemoteAddress()+"上线");

                        }

                        if (key.isReadable()){ //通道发送read事件，即通道是可读的状态
                            //处理读(专门写方法。)
                            readData(key);

                        }

                        //当前的key删除，防止重复处理
                        iterator.remove();
                    }


                }else {
                    System.out.println("等待。。。");
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //发送异常处理
        }
    }

    //读取客户端消息
    private void readData(SelectionKey key){

        //取到关联的channel
        SocketChannel channel = null;

        try {
            //得到channel
            channel = (SocketChannel) key.channel();
            //创建buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);

            int count = channel.read(buffer);
            //根据count的值做处理
            if (count>0){
                //把缓存区的数据转成字符串
                String msg = new String(buffer.array());
                //输出该消息
                System.out.println("form 客户端"+msg);
                //向其他的客户端转发消息(去掉自己)，专门写一个方法来处理
                sendInfoToOtherClients(msg,channel);
            }
        } catch (IOException e) {
            try {
                System.out.println(channel.getRemoteAddress()+"离线了。。");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

    private void sendInfoToOtherClients(String msg,SocketChannel self) throws  IOException{

        System.out.println("服务器转发消息中。。");
        //遍历 所有注册到selector上的SocketChannel，并排除self
        for (SelectionKey key : selector.keys()){
            //通过 key取出对应的SocketChannel
            Channel targetChannel = key.channel();

            //排除自己
            if(targetChannel instanceof SocketChannel && targetChannel != self){
                //转型
                SocketChannel dest = (SocketChannel) targetChannel;
                //将msg存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer的数据写入通道
                dest.write(buffer);
            }
        }

    }

    public static void main(String[] args) throws Exception {
        //创建服务器对象
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();

    }
}
